Brake cylinders of this type are used, inter alia, in rail vehicles. There, they are frequently used to actuate a brake caliper, with the aid of which brake linings are pressed onto a brake disk. Here, the piston stroke is to always be approximately equally great, independently of the wear of the brake linings. For this purpose, an adjusting device is usually provided which has a spindle which is guided in a piston tube and an adjusting nut. An axial force is exerted on the spindle by a spring, which axial force attempts to pull the spindle out of the adjusting device. Since the spindle and the adjusting nut are connected to one another via a thread which is not self-locking, a torque acts on the adjusting nut as a result of the spring force.
During the normal braking operation, the adjusting nut is blocked in such a way that only a linear movement together with the spindle in the direction of the longitudinal center axis of the brake cylinder is permitted, but not a rotational movement. A rotation of the adjusting nut may only be permitted for the adjusting operation when a certain wear of the brake linings has taken place. In order to control the rotational movement of the adjusting nut during the initiation of a braking operation, what is known as a control sleeve is used which is arranged within the piston tube such that it can be displaced on the spindle. The torque is transmitted from the control sleeve to the piston tube via integrally formed locking arms which are guided in open slots of the piston tube. During the braking operation, in contrast, the torque of the adjusting nut is transmitted directly to the piston tube.
The piston tube is connected fixedly to the piston, with the result that the torque is transmitted from the piston tube to the piston. The torque is introduced into the housing via guide pins which are attached to the piston and which correspond with appropriate guides in the housing. This force transmitting connection between the piston and the piston tube leads to a complicated and expensive component which is difficult to mount. The dismantling, mounting and the components to be replaced are relatively expensive even in the case of reconditioning of the pneumatic cylinder.
In the case of another known brake cylinder, the locking arms of the control sleeve are supported on a stop ring which is screwed into the cover of the cylinder. Here, the torque which acts on the adjusting nut is transmitted via the locking arms into the housing of the brake cylinder not only in the rest position but also during the braking operation, since the piston tube is also supported on the locking arms via the open slots. The control sleeve and the integrally formed locking arms therefore have to be of very solid and stable configuration.
In the case of two previously known brake cylinders, the adjusting device cannot be premounted as one unit on account of the locking arms which are integrally formed onto the control sleeve.